There are two setups for a generator:
1) Automatic transfer switch
2) No ATS - Manual transfer
In the normal setup (not rednecked/modded/whatever you call it) where there is no ATS, then the shore power cord must be plugged into one of two places:
1) Shore power
2) A receptacle where power is supplied by the generator located in the shore power cord storage location. (or similar)
Therefore, if the shore power cord is plugged into shore power, and the power goes off, starting the genny powers nothing. The user must unplug from shore power and plug it to the generator output receptacle to power the RV.
There is no chance of backfeeding the grid with this setup.
I have an RV that does not have an ATS. Every RV I've seen has an ATS or a receptacle - Automatic or manual power transfer... it is still transferred.